Here's a breakdown of Earth's layers:

* Inner Core: Solid iron and nickel at extremely high temperatures and pressure.

* Outer Core: Liquid iron and nickel.

* Mantle: The thickest layer, composed of mostly solid rock but with a partially molten layer called the asthenosphere.

* Crust: The thin, outermost layer, composed of solid rock.

The mantle is a fascinating layer with a significant role in Earth's processes, including plate tectonics and volcanic activity.